ZME is cross coupled for most of its sectors, VHF only. In my area, cross coupling is enabled on the high and ultra high sectors when sectors in like altitude strata are combined. Some of the other areas are set up differently because they combine their sectors in different ways. For instance, in my area we can cross couple sector 25 with 26, and sector 33 with sector 34. When we combine up the high and ultra high at about 2330 or so, you can still get an airplane on ultra high stepping on one on high, but the system has greatly improved things, particularly during the FedEx pushes on the mid shift.

There are also some other odd technical limitations, sectors that have multiple transmitter sites cannot cross couple with another frequency. I find it odd that with the amount of money and technology in the VSCS system that they can't get the software or hardware responsible for doing cross coupling to simply use the selected transmitter. In our last briefing about it, we were told that there is no near term plan to resolve that issue.

I noticed the other day ZDC was cross-coupling a couple of their high sectors (127.92/121.92) while at the same time the adjacent high sector to the north was merged with some low sectors but not cross-couple with them. (maybe for the reasons you mentioned ?).

Down here in Florida the sector above Freeport Bahamas is cross coupled between a low and high sector for the most part(125.325 and 133.4). After 9 PM is when we go all in cross couple mode with 132.45 and 135.175 linking up and after 10 PM we see all of the Eastern high sectors linking up 134.35,119.825,133.4,125.325,132.15,132.25,126.95,and 134.8 on 119.825, while overland Florida late at night is handled by 132.45 the RCAG out of Pahookee. The southern extent of my radio range seems to be 126.325,126.275 and 127.225 as cross coupled. Western sectors 133.9,128.225,132.35,and 132.4 all link up on 133.9 overnight and 132.2 links up with 133.5 and 124.7. In all this fracus it seems ZMA works with 5-7 controllers overnight.

I noticed the other day ZDC was cross-coupling a couple of their high sectors (127.92/121.92) while at the same time the adjacent high sector to the north was merged with some low sectors but not cross-couple with them. (maybe for the reasons you mentioned ?).

That is correct. In the current implementation, you can only cross couple two frequencies. So usually (but not always) the cross coupling is done with sectors in the same strata. I'm going to assume that in your example, the high altitude sectors are combined with each other more often than the high and lows, or the low sector in question may have two available RCAG sites, and therefore can't be cross coupled.

Let me see if I understand this... are they actually repeating aircraft transmissions over another frequency, or simply ganging up receivers for the controller and simulcasting his transmissions over several frequencies? In other words, can you hear everybody on any of the coupled frequencies? You can hear a carrier "squelch tail" after aircraft transmissions? If so, I wonder how they keep the controller from stepping on himself. What I can imagine is all transmissions, including the controller transmissions, on "A" being repeated onto "B", with the controller transmitting "A" and listening on "B" (or both). That would be the simplest implementation, but aircraft on "A" would only hear themselves and the controller, and those on "B" would hear everything. For everybody to hear everybody they would mute all the receivers while the controller transmits on all channels and then have any aircraft reception on any channel repeated over all the other channels.

I guess what doesn't make sense to me is why the need for aircraft to hear other aircraft not in their airspace... only possible benefit being not having to change frequencies when going through a large sector. It seems to me that ganging up multiple channels under one controller simulcasting on all of them the way have have been doing for years at night works just fine.

It repeats the pilot's transmissions from one frequency to another, so to a pilot, it sounds as if they are all on the same frequency, and hopefully won't step on each other as much. Nothing is as frustrating as trying to issue a control instruction and having the read back stepped on time after time because another pilot on the other frequency you are using thinks his check in is so important that he keys up every time you unkey the mic. That is one of the few times I'll snap at a pilot on frequency.

For the most part, it really does work well. You still get the occasional pilot who transmits as soon as they switch frequencies, which no amount of technology is going to be able to resolve, but it has reduced the frequency of pilots stepping on each other.

In the current implementation, you can only cross couple two frequencies.

I'm surprised to hear in the US you can only cross-couple 2 frequencies at a time. In some other areas of the world I'm familiar with, Canada, Europe, Australia, it is quite common to hear multiple frequencies cross-coupled at a time.

As an example Montreal Center merges all their northern sectors in the overnight hours and cross-couples around 16 frequencies at once. You can listen to it here on LiveATC - YUL ACC (Noranda Sector) feed. For some reason, the adjacent airspace to the west controlled by Edmonton merges their sectors as well using multiple frequencies but they don't use cross-coupling. Different system maybe ?

YoungBlood, so it is a true cross repeater, and when you transmit from the ground you transmit on all frequencies and override any airborne audio, the advantage being that now the pilots know how busy you really are.

As to the technology to force pilots to listen before talking, that would actually be pretty simple... with the exception of guard channels all radios would be required to disable the transmitter for 30 seconds after a frequency change, and any time the transmitter is engaged while a signal is being received the low oil pressure warning light comes on.

Or cut the ignition... anything to get them off the radio immediately. I can see him key up... the engine cuts out and comes back the instant he un-keys, which would be immediately, of course, then he would be off the air for a few minutes trying to figure out what just happened. Kind of like the crap my instructor used to do with me, cranking the DG, pulling breakers, turning on the panel lights in the daytime so you couldn't see the dimmed gear indicator bulbs, and dicking around with the radios and audio panel while I was not looking. I eventually got even with him, big time.

Ha ha! My instructor was good for pulling breakers on me every now and then. To this day I can't figure out how he did that without me seeing it. Then there was the time he told me to slow to the point where the stall warning came on. Then he asked me to floor the left rudder pedal...he wanted to show me how to recover from a spin. Next thing I knew the bottom dropped out from under us and I was staring at the Long Island Sound rotating in the front wind shield...scared the crap out of me. My instructor thought it was funny...